Thermal transfer printer for printing on both sides of a paper sheet

Abstract

A thermal transfer printer capable of printing on both sides of a sheet of paper includes first and second transferring rollers, first and second guide paths, and a paper-ejection path. The paper is repositioned for printing on the reverse side, after the front is completely printed.

What is claimed is: 
     
       1. A thermal transfer printer operative for printing on both sides of a sheet of paper, comprising: a rotatable platen drum;   a recording head positioned over said platen drum, having means for emitting heat in a predetermined pattern, and mounted so as to move up and down so that said heat emitting means is brought into contact with said platen drum;   an ink ribbon coated with sequential sections of predetermined color pigments and transferred between said recording head and said platen drum;   first transferring means for laterally transferring the sheet of paper between said ink ribbon and said platen drum;   second transferring means for repositioning the sheet of paper after one side of the sheet of paper is completely printed and for laterally transferring the sheet of paper between said platen drum and said ink ribbon for printing on an opposite side of the sheet of paper; and   means for ejecting the sheet of paper,   wherein said first transferring means comprises: a capstan roller disposed at one side of said platen drum;   a pinch roller for friction-rotating with said capstan roller;   a pair of first transferring rollers installed at another side of said platen drum;   a paper-supply path for guiding the sheet of paper between said capstan roller and said pinch roller;   a first guide path for guiding the sheet of paper from said platen drum, and having a rear portion at which said first transferring rollers are installed; and   a second guide path having one end which opens toward said capstan roller and an opposite end which communicates with said first guide path.     
     
     
       2. The thermal transfer printer as claimed in claim 1, wherein said second transferring means comprises: a paper ejection path for ejecting the sheet of paper from said capstan roller and said platen drum; and   a pair of second transferring rollers installed in said second guide path.   
     
     
       3. The thermal transfer printer as claimed in claim 2, further comprising: a first sensor, installed in front of said capstan roller, for sensing either end of the sheet of paper; and   a second sensor, installed in front of said first transferring rollers, for sensing a trailing edge of the sheet of paper.   
     
     
       4. The thermal transfer printer as claimed in claim 1, further comprising: a first sensor, installed in front of said capstan roller, for sensing either end of the sheet of paper; and   a second sensor, installed in front of said first transferring rollers, for sensing a trailing edge of the sheet of paper.   
     
     
       5. A thermal transfer printer operative for printing on both sides of a sheet of paper, comprising: a rotatable platen drum;   a recording head positioned over said platen drum, having means for emitting heat in a predetermined pattern, and mounted so as to move up and down so that said heat emitting means is brought into contact with said platen drum;   an ink ribbon coated with sequential sections of predetermined color pigments and transferred between said recording head and said platen drum;   first transferring means for laterally transferring the sheet of paper between said ink ribbon and said platen drum;   second transferring means for repositioning the sheet of paper after one side of the sheet of paper is completely printed and for laterally transferring the sheet of paper between said platen drum and said ink ribbon for printing on an opposite side of the sheet of paper, wherein said second transferring means comprises: a paper-ejection path for ejecting the sheet of paper from a capstan roller and said platen drum;   a second guide path having one end which communicates with said paper-ejection path and another end which opens toward said capstan roller and a pinch roller; and   a pair of second transferring rollers installed in said second guide path;     means for ejecting the sheet of paper;   a first sensor, installed in front of said capstan roller, for sensing either end of the sheet of paper; and   a second sensor, installed in front of said first transferring rollers, for sensing a trailing edge of the sheet of paper.   
     
     
       6. A thermal transfer printer operative for printing on both sides of a sheet of paper, comprising: a rotatable platen drum;   a recording head positioned over said platen drum, having a heat emitting device for emitting heat in a predetermined pattern, and mounted so as to move up and down so that said heat emitting device is brought into contact with said platen drum;   an ink ribbon coated with sequential sections of predetermined color pigments and transferred between said recording head and said platen drum;   a first transferring mechanism including a capstan roller and a pinch roller disposed at one side of said platen drum, and a first guide path for guiding the sheet of paper from said platen drum, said first transferring mechanism laterally transferring the sheet of paper between said ink ribbon and said platen drum;   a second transferring mechanism including a paper-ejection path for ejecting the sheet of paper from said capstan roller and said platen drum, a second guide path having one end which communicates with said first guide path and with said paper-ejection path and another end which opens toward said capstan roller and said pinch roller, and a pair of transferring rollers installed in said second guide path, said second transferring mechanism repositioning the sheet of paper after one side of the sheet of paper is completely printed and for laterally transferring the sheet of paper between said platen drum and said ink ribbon for printing on an opposite side of the sheet of paper; and   an ejecting device which ejects the sheet of paper.